Electric furnace.



.1. W. BROWN.

ELECTRIC FURNACE.

APPLICA'HON FILED mm). 1912.

1,143,940. Patented June 22, 1915.-

INVENTOR A1TORN BY UNITED STATES PATENT OFFICE.

JOHN W. I BROWN, OF LAKEWOOD, OHIO, ASSIGNOR TO NATIONAL CARBON COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF NEW JERSEY.

ELECTRIC FURNACE.

Specification of Letters Patent.

Patented June 22, 1915.

Application filed January 8, 1912. Serial No. 670,072.

To all whom it may concern Be it known that I, JOHN W. BROWN, a residentof Lakewood, in the county of Cuyahoga, in the State of Ohio, have invented new and useful Improvements in Electric Furnaces, of which the following is a clear and exact description.

This invention relates to improvements in electric furnaces and more particularly to continuous electric furnaces for calcining granular materials such as various cokes and for manufacturing graphite.

The temperature attained in an electric furnace for the production of graphite especially, is high enough to volatilize the ash, and if no meansare provided for condensing the volatile matter, the cool charge above the heating region will condense it. The result is that the condensed ash descends with the charge into the heating region where it is volatilized along with the ash originally in the charge. The condensation and volatilization will continue till the charge becomes so contaminated that the furnace will be ultimately clogged up by the accumulating ash.

When petroleum coke is used as the furnace charge the percentage of ash is not high enough to cause much trouble, but when coke made from coal is used this objectionable feature becomes serious, as such coke contains a high percentage of ash.

To overcome the difficulty is the purpose of my invention, and the manner in which it is done will be explained in the following description, particular reference being had to the drawings in which:

Figure 1 shows a sectional elevation of a cone type of fm'nace with my invention applied thercto. Fig. 2 shows a sectional elevation of a slightly different cone type of furnace with my improvement. Fig. 3 sholws a detail of the floor on a much smaller sea 0.

Referring to Fig. l, the outer walls of the furnace are indicated by 1. These will be made of firebr-ick or any other good heat resisting and insulating material. Within the furnace is a channel member 2, preferably formed of carbon to withstand the high temperatures attained in the furnace. This channel rests on the base of the furnace and extends upward. to the'electric heating recentral aperture 4 which is relatively small as compared with the diameter of the furnace. The size of the aperture, however, can be varied to suit the purpose for which the furnace is used.

The floor 3 is used as one of the electrodes and may be connected to one of the poles of any source of E. M. F., either direct or alternating. Extending through the walls 1 are shown two electrodes 7. These are of the same polarity and are to be connected to the other terminal of the source of E. M. F.

They are joined to the inner channel 2 by means of threads, or any other means may be used for forming a good connection. The electrodes 7 have connections 8 fastened thereto. The upper part of the furnace'contains a conical or funnel shaped member 9 that is supported by the walls 5. This member may be braced to the walls by means of supports made of firebrick or by any other well known way. The particulars of the bolted or otherwise fastened together. The

cover 11 has a central opening normally closed by a lid 13 and a plurality of openings l4 and 15 for admitting the furnace charge from hoppers 16 and l7. The charge may be conveyed to the hoppers by conveyers or in any other way. The space between the channel 2 and the outer walls 1 is filled with. granular carbon material, curborundum or other similar substance, to the level of the top of the electrode 7 for preventing the loss of heat from the furnace.

it-h the structure disclosed there is a space 17 extending around the channel 2 between the upper part of the electrodes 7 and the floor electrode 3, and there is a space 18 between the floor electrode 3 and the member 9 and a third space 19 within the member 10. These all serve as condensers for condensing the volatile ash and other impurities in the furnace charge. The

vapor arising from the electric heating zone will partly pass through the opening be tween the channel 2 and the floor 3, Where it will be condensed on the Walls of the chamber 17. The condensed material can be removed by pulling out the blocks spaced at various places around the circum ference of the furnace. Part of the volatile matter will pass up through the charge 'in the opening 4 and escape into the chamber 18 where it will be condensed, either on the member 9 or on the walls of the furnace. This material can be taken from the furnace floor with suitable tools, by removing the blocks '21 placed at various places around the furnace. The volatile matter that passes up through the charge in the opening 4 will not be condensed thereon for this region is intensely heated. If there is any volatile matter that escapes through the opening 12, it will be condensed in the chamber 19. The condensed material can be taken out with tools by removing the cover 13.

The condensing chambers will serve the purpose without any further arrangement, but in order to facilitate the passage of the volatile matter into the condensing chambers the'following system may be used. The fan or pump 22 forces an inert gas through the pipes 23 and ill, and holes in the electrodes 7, into the furnace charge. Gas is also forced through pipes 25 into the charge be-' low the electrodes. This gas is removed from the condensing chamber 17 at various places in the circumference by pipes 26. The gas is removed from condenser 18 by means of pipes 27 and from condenser l9 by pipe On account of this arrangement a pressure will be maintained in the charge itself, and a vacuum or reduced pressure maintained in the condensing chambers. This will cause the volatile matter to flow from the charge into these chambers. If it is found that the gas coming from the condesing chambers is too highly heated it may he led through pipes in the descending cool charge in the upper part of the furnace to remove the heat therefrom, and at the same time preheat thcfurnace charge, as is shown in Fig. 2.

(last-s. may also be forced down through the untreated charge and for this purpose I have shown a pipe Ii connected to the pipe 2i. This prevents volatile matter from passing up into the untreated charge and hence it cannot con'lcnscthereon.

My invention is not to be understood limited to the cone type of furnace or any other particular type. lt can he applied to an electric t'urniu'c. I have shown my inwntion applied to the cone type for the reason that I regard this type as especially cllicient, since the current flows from the lloor member 3 through the constricted portionof the cone shaped charge to the channel 2 and electrode 7, and an intense heat is produced in the constricted portion of the charge. With this type of furnace graphitization can be carried on very readily.

If it is found desirable to draw all of the volatile matter into chamber 17, the valves 29 in the pipes 27 and 28 may be closed so that no vacuum is maintained in the chambers 18 and 19. Gas would then be forced in through the pipes 23, 25 and 36 and drawn through pipes 26. Valves are shown in all of the pipes so that the passage of gas therethrough may be shut off or regulated to any extent. Any one of the chamhers may thus be used if desired.

At the base of the furnace is shown I; conveyer 30 for removing the material to the outside of the furnace. By making the furnace of sulicient height the charge may be cooled Without the use of any cooling means. However, water pipes 31 may be used to aid in cooling of the furnace product if desired.

Fig. 2 differs from Fig. 1 only in the c0n struction of the furnace above the floor electrode 3, and in the manner in which the gases are removed from the lower condenser" 17 The material descending from the hoppers 16 passes directly into the space within the walls 5. A condensing member 32, preferably formed of some high heat resisting material such as carbon or silicon carbid, extends through a hole in the cover 11. This serves as the condenser for the material passing up through the opening in the floor electrode 3. A vacuum or reduced pressure is maintained in the condenser 32 to draw in the volatile matter arising from the heat-'- ing zone. When it is necessary to remove the material condensed in this member it may be taken from the furnace and cleaned out. Vl hen it is placed liihk in the opening in the cover plate 11, it will rest on the fur nace charge, and will descend therewith until the lugs 233 stop further movement. The condensing member 32 may in some cases be made of iron. In this figure the gases from the condenser 17 are returned through pipes that extend up through the cool descending charge. This cools the gases and prehcats the charge.

The connection l'ictwccn. the pipes and the member 32 of Fig. 2 and member 13 of Fig. 1 may be llcxible'to admit of their removal or the pipe conncctimi may have a joint that is rcadily disconnected.

ln Fig. l l have illustrated the floor electrode in a somewhat conventional manner, but in Figs. 2 and I) I have shown one Way in which this lloor may be constructed. The floor is built up by a plurality of carbon slabs 34; resting on lodges in the Walls 1, and on carbon slabs 35 running cross-Wise. One end of the slabs rests on an abutment or ledge and the other projects through the wall and has a connector 6 for attaching the terminals of a source of E. M. F. The two terminals 6 of this figure would be connected together to the same terminal.

Having described my invention what I claim is:

1. In an electric furnace, the combination with electrodes of a condensing chamber within the furnace, adapted to collect and condense the volatilized impurities from a charge and means for maintaining a reduced pressure in the chamber whereby the volatile matters are drawn into the chamber from the furnace charge.

2. In an electric furnace, upper and lower electrodes for heating a charge, and a condensing chamber surrounding the heating zone.

3. In an electric furnace, upper and lower electrodes for heating a charge, a condensing chamber surrounding the heating zone and means whereby the condensed materials may be removed without removing either of the electrodes.

4. In an electric furnace, inclosing walls, an upper floor electrode, an electrode below said floor electrode, and means cooperating therewith to form a condensing chamber for volatile matter arising from the furnace charge.

5. In an electric furnace, inclosing walls, a floor electrode, means cooperating therewith to form condensing chambers above and below the floor electrode.

6. In an electric furnace, inclosing walls, a floor electrode, means cooperating therewith to form condensing chambers above and below the floor electrode and means for maintaining reduced pressures 1n the condensing chambers.

7. In an electric furnace, inclosing walls, a channel within said walls, a floor electrode above the channel, and a member above the floor electrode, the space between the memher and the floor electrode serving as a condensing chamber.

8. In an electric furnace, inclosingwalls, a floor electrode, means cooperating therewith to form condensing chambers above and below the floor electrode, a third condensing chamber in the upper part of the furnace and means for maintaining reduced pressures in all said chambers.

9. In an electric furnace, inclosing walls, a floor electrode, means cooperating therewith to form a condensing chamber beneath the floor electrode, a removable condensing chamber in the charge above the floor electrode, and means for maintaining reduced pressures in said chambers.

10. in an electric furnace, horizontal elec trodes, and a condensing chamber in the furnace charge above the electric heating zone, said condenser being spaced from the upper electrode to permit the charge to pass around it and between the electrodes.

11. In an electric furnace, inclosing walls, horizontal heating electrodes, and a removable condensing chamber in the furnace charge above the heating zone, said chamber having an opening in close proximity thereto and being independentof the electrodes whereby it may be removed without disturbing them.

12. In an electric furnace, inclosing walls, a lower electrode, a horizontal upper electrode, and a condensing chamber above the upper electrode suspended from the inthe untreated charge in the direction of its movement.

15. In an electric furnace, the combination of electric heating means, a condensing chamber and means for forcing a gas through the untreated charge to prevent volatile matters from condensing thereon.

16. In a continuous electric furnace, the" combination of'electrlc heating means,

condensing chamber and means for forcing a gas through theuntreated charge in the direction of its movement to prevent olatile matters from condensing thereon.

17. In an electric furnace, a floor electrode built up of a plurality of sections and having an opening to allow the charge to pass therethrough.

18. In an electric furnace, inclosing walls, a floor made up of a lurality of conducting bars, said floor having an opening to allow the charge to pass therethrough, and conducting bars beneath said floor to convey the current thereto.

19. In an electric furnace, a floor electrode built up of a plurality of horizontal transverse sections, and having an ,opening to allow the charge to pass therethr ough.

In testimony whereof I have hereunto ed my name. JOHN W. naown.

Witnesses:

F. D. LAWRENCE, H. H. H. MAY. 

